Research Article: Reliability, convergent validity and factor structure of the DASS-21 in a sample of Vietnamese adolescents

Date Published: July 19, 2017

Publisher: Public Library of Science

Author(s): Minh Thi Hong Le, Thach Duc Tran, Sara Holton, Huong Thanh Nguyen, Rory Wolfe, Jane Fisher, Ali Montazeri.


To assess the internal consistency, latent structure and convergent validity of the Depression, Anxiety and Stress Scale-21 (DASS-21) among adolescents in Vietnam.

An anonymous, self-completed questionnaire was conducted among 1,745 high school students in Hanoi, Vietnam between October, 2013 and January, 2014. Confirmatory factor analyses were performed to assess the latent structure of the DASS-21. Factorial invariance between girls and boys was examined. Cronbach alphas and correlation coefficients between DASS-21 factor scores and the domain scores of the Duke Health Profile Adolescent Vietnamese validated version (ADHP-V) were calculated to assess DASS-21 internal consistency and convergent validity.

A total of 1,606/ 1,745 (92.6%) students returned the questionnaire. Of those, 1,387 students provided complete DASS-21 data. The scale demonstrated adequate internal consistency (Cronbach α: 0.761 to 0.906). A four-factor model showed the best fit to the data. Items loaded significantly on a common general distress factor, the depression, and the anxiety factors, but few on the stress factor (p<0.05). DASS-21 convergent validity was confirmed with moderate correlation coefficients (-0.47 to -0.66) between its factor scores and the ADHP-V mental health related domains. The DASS-21 is reliable and suitable for use to assess symptoms of common mental health problems, especially depression and anxiety among Vietnamese adolescents. However, its ability in detecting stress among these adolescents may be limited. Further research is warrant to explore these results.

Partial Text

It is reported that mental disorders, including depression, are among the top 20 leading causes of disability worldwide [1]. All over the globe, about 400 million people are affected by depression [2] and around 10–20% of the world’s children and adolescents suffer from mental disorders [3]. These disorders may result in impaired capacity to study and work and even suicide among the sufferers if untreated [2]. Early detection of these conditions is therefore of great importance.

A total of 1,616/ 1,745 (92.6%) students returned a completed questionnaire. Out of those who did not participate, 120 were absent on the survey day; seven students and two parents refused participation. Complete responses for the DASS-21-V were available for 1,387 students (85.8%) and the analysis was restricted to these individuals. Socio-demographic characteristics of the analysis sample are presented in Table 1.

In this study, the factor structure and evidence about the convergent validity of the DASS-21 Vietnamese validated version among a large sample of Vietnamese adolescents is presented for the first time. The results demonstrate that the DASS-21-V is reliable and shows acceptable convergent validity among these adolescents. We also found that a four-factor latent structure (4F model 7), representing general distress, depression, anxiety and stress factors, best fit the data among these students. The results are robust with a systematically recruited, large sample, participants representing students from three main types of high schools and institutions in Vietnam, a high response rate and a low level of incomplete data.

Overall, the results from this study provide evidence that the DASS-21-V is suitable for use as a screening tool for symptoms of common mental health problems, especially Depression and Anxiety among adolescents in Vietnam. The study also extends knowledge on the reliability and convergent validity of the DASS-21-V among Vietnamese people. We recommend the use of a total DASS-21 score to represent symptoms of general distress when applied among Vietnamese adolescents. The use of subscale scores of Depression and Anxiety among them is also acceptable. Nevertheless, the DASS-21-V to detect symptoms of stress among Vietnamese adolescents should be used with caution. Future research in which the DASS-21-V is compared against a standard diagnostic instrument for common mental disorders would be helpful in confirming its validity for use among Vietnamese adolescents. Revision of items or even substitution of new items specific to these constructs among adolescents should be considered in such research.




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